>> that is absolutely correct and also those with chronic diseases, like heart disease or diabetes. >> dr. joan krikava, thank you for helping us. lisa, it's surprising how these germs can easily spread. >> wolf, this goes without saying. if you suspect that someone has the flu, keep your distance. the flu is passed by droplets but it can also be passed by touching a surface with the flu virus on it. we touch so many things without even realizing it. take a simple trip on the subway. buying a metro card, going down the escalator, that's only the beginning. the flu virus can spread easily in an enclosed space like a subway station. >> the virus is usually spread threw contact, so any time we cough or sneeze when we're infected with the virus, we can be contagious to anyone not affected. >> reporter: the flu virus can spread to others up to six feet away. and flu germs can remain suspended in the air. the top three ways to catch the flu, being near someone who is sick who sneezes, coughs, or talks spreading infected droplets, drinking from the same cup or sharing a utensil or touching a